<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .demo {
            background-color: orange;
        }
    </style>
</head>

<body>
    <button id="btn">点我创建一个输入框</button>

    <script type="text/javascript">
        const btn = document.getElementById("btn");
        btn.onclick = () => {
            const input = document.createElement('input');
            input.className = "demo";
            input.value = 99;
            input.onclick = () => { alert(1) };

            document.body.appendChild(input);

            input.focus();
            // input.parentElement.style.backgroundColor="skyblue";
            console.log(input.parentElement);
        }
    </script>

</body>

</html>